Effect of four non-ionic contrast media on red blood cells in vitro. II. Aggregation.

The newly synthesized non-ionic monomeric iopentol and dimeric iodixanol were compared with the non-ionic monomers iopamidol and iohexol in both original hypertonic and isotonic solutions at a constant hematocrit of 35%. All contrast media at all volume ratios (contrast medium/blood) decreased red blood cell aggregation with no difference between the various contrast media. The degree of disaggregation of red blood cells increased with increasing concentration of contrast medium in solution. At the lowest volume ratio (2%) red blood cell aggregation was near that of normal blood. At the volume ratio 50% the disaggregatory effects following both isotonic and hypertonic solutions were pronounced. At a high molar concentration both the isotonic iodixanol and the hypertonic solutions of iohexol, iopentol and iopamidol induced an almost total inhibition of red blood cell aggregation. This indicates that the concentration of contrast medium (chemotoxic effect) for non-ionic contrast media is more important for the disaggregatory effect than the osmolality.